17 



T»ti M_ J « * ^ The versatile anthers are borne on 



Tall Meadow Oat-Grass. 



long filaments and are set in 

 motion by the slightes breeze, which causes the pollen to bo 

 shaken out in clouds. The stigmas are long and plumose 

 and readily catch the pollen. As in corn, the flowers are 

 proterogynous and by the time pollen is mature the stigmas 

 are withered. 



A large number of our woody plants are 

 ^ ■ pollinated by the wind— the hazel, birch, 



pine, Cottonwood, oak, elm, etc. 



Hazel ^^ °^^ °^° Hazel (Corylus Americana Walt.) the 

 staminate catkins are pendent, the pistils occur in 

 short erect cones quite inconspicuous, the stigmas are red. A 

 great abundance of pollen is produced. Our Hazel flowers 

 in early April. In the European hazel nut {Corylus avellana) 

 the staminate flowers are borne in drooping cylindrical cat- 

 kins, each flower containing eight stamens with short fila- 

 ments. The anthers contain an abundance of pollen. The 

 pistilate flowers are not conspicuous, several occurring in a 

 scaly bud. The stigmas are of reddish color and large. 

 Many wind pollinated flowers have red stigmas 

 but these are to be explained on physiological 

 grounds. The flowers may be proterandrous or 

 preJterogynous. As a general rule, in wind pollinated trees 

 bloom-before the leaves are out, because the leaves interfere 

 with the distribution of pollen. As Robertson says: 

 "In the case of the wind pollinated trees it is obvious that if 

 the leaves were developed before the flowers, the process of 

 pollination would be greatly impeded by the leaves interfer- 

 ing with the free circulation of the wind and catching the 

 pollen which is intended for the stigmas." 



